Design method of profiled blade root precision milling cutter

Abstract

The application discloses a design method of a bacteria type blade root fine milling cutter and relates to the field of bacteria type blade root machining. The method is characterized in that, under the premise conditions that the middle of the wheel groove top is a plane, the two sides of the plane are inclined surfaces to make the wheel groove top and the side surface transition, the maximum overcut amount Tmax is less than 0.01 mm, and the inclination slope K0 of the inclined surfaces on the two sides of the wheel groove top area is greater than the slope K1 of the non-working surface of the blade root top, the overcut amount is compensated in the pitch δ of the cutter when the cutter is designed. Specifically, the pitch δ of the cutter is equal to the pitch d of the non-working surface of the blade root and the working surface of the blade root minus the maximum overcut amount Tmax. The pitch d is obtained according to the design drawing of the blade root. The application can process the blade root meeting the product drawing size and assembly requirements under the premise of actual overcut, and ensures the product quality.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of turbine profile blade root processing, and particularly to a design method of a profile blade root fine milling cutter. BACKGROUND

[0002] The profile blade root has a working surface and a non-working surface. When the profile blade root is assembled with the wheel groove, the non-working surface on the first tooth of the blade root and the top of the wheel groove need to have an assembly gap, which is referred to as the wheel groove top gap, and the size requirement of the wheel groove top gap needs to be met. The working surface on the first tooth of the blade root is tightly fitted with the wheel groove.

[0003] The cutter designed by the traditional method has a circular arc path when machining the working surface of the blade root. The cutter only contacts the highest point of the circular arc, and the cutter does not interfere with the blade root. However, when machining the non-working surface of the blade root, the cutter interferes with the blade root except for the center point of the cutter due to the direction of the circular arc in the cutter path, and overcutting occurs during machining. The assembly gap between the overcut blade root and the wheel groove becomes larger, which does not meet the product drawing size and assembly requirements. SUMMARY

[0004] The present application aims to provide a design method of a profile blade root fine milling cutter, which can meet the product drawing size and assembly requirements of the blade root under the premise of actual overcutting, and ensure product quality.

[0005] The technical solution adopted by the present application is as follows: a design method of a profile blade root fine milling cutter, the prerequisite conditions are that the middle of the wheel groove top is a plane, the two sides of the plane are inclined surfaces to make the wheel groove top and the side surface transition, the maximum overcutting amount Tmax is 0.01mm less than the overcutting amount T1 of the non-working surface of the blade root at the wheel groove top plane, and the inclination slope K0 of the inclined surfaces on both sides of the wheel groove top region is greater than the slope K1 of the non-working surface of the blade root.

[0006] When designing the cutter, the overcutting amount is compensated in the pitch δ of the cutter. Specifically,

[0007] The pitch δ of the cutter is d minus the maximum overcutting amount Tmax.

[0008] Wherein, d is obtained according to the design drawing of the blade root.

[0009] The blade root has a U-shaped notch with a step, and the bottom of the notch is the top of the blade root. The wheel groove is a boss matched with the shape of the notch, and the wheel groove is assembled in the notch of the blade root after assembly.

[0010] After the wheel groove and the blade root are assembled, there is an assembly gap of 0.03-0.08mm between the wheel groove top and the blade root top.

[0011] Further, obtain Tmax;

[0012] According to Obtain the maximum overcut amount Tmax; wherein:

[0013] R: the radius of the non-working surface arc of the blade root; r0: the radius of the tool at the machined non-working surface;

[0014] R and r0 are obtained according to the design drawings of the blade root.

[0015] Further, 2r0 should be less than the width of the top plane of the blade root.

[0016] Further, obtain T1;

[0017] According to Obtain the overcut amount T1 of the non-working surface of the blade root at the top plane of the wheel groove; wherein:

[0018] w: the width of the top plane of the wheel groove; w is obtained according to the design drawings of the wheel groove.

[0019] Further, obtain K0;

[0020] Obtain the inclination slope of the inclined surface on both sides of the top area of the wheel groove according to K0=tanα; wherein:

[0021] α: the inclination angle of the inclined surface on both sides of the top area of the wheel groove; α is obtained according to the design drawings of the wheel groove.

[0022] Further, obtain K1;

[0023] According to Obtain the slope of the top non-working surface of the blade root.

[0024] In summary, due to the adoption of the above technical scheme, the beneficial effects of the present application are:

[0025] The tool designed by the method can ensure that the difference between the actual machined distance between the working surface and the non-working surface of the blade root and the designed distance d between the working surface and the non-working surface of the blade root is within the allowable range, which is equivalent to the actual machined distance between the working surface and the non-working surface of the blade root being equal to the designed distance d between the working surface and the non-working surface of the blade root; the blade root meeting the product drawing size and assembly requirements can be machined under the premise of actual overcut, and the product quality is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0026] The present application will be described by examples and with reference to the accompanying drawings, in which:

[0027] Figure 1 The blade root structure and related parameters disclosed by the present application are shown in the schematic diagram;

[0028] Figure 2 A schematic diagram of the wheel groove structure and related parameters disclosed in the present invention;

[0029] Figure 3 This is a schematic diagram of the assembly of the blade root and the wheel groove disclosed in the present invention;

[0030] Markings in the figure: 1-blade root; 11-blade root non-working surface; 12-blade root working surface; 2-wheel groove. DETAILED DESCRIPTION

[0031] All features disclosed in this specification, or all steps in the disclosed methods or processes, except mutually exclusive features and / or steps, can be combined in any manner.

[0032] Any feature disclosed in this specification, unless otherwise stated, may be replaced by other equivalent or similar features. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0033] like Figure 1 - Figure 3 As shown, a design method for a fungus-shaped blade root fine milling cutter is used to process a certain type of blade root 1 as an example. The blade root 1 has three teeth, which are arranged in sequence from top to bottom and have gradually increasing geometric dimensions. The middle of the blade root 1 is a notch for assembling the wheel groove 2.

[0034] Specifically, the blade root 1 has a U-shaped stepped notch, the bottom of the notch is the top of the blade root 1; the wheel groove 2 is a boss that matches the shape of the notch, and after assembly, the wheel groove 2 is assembled in the notch of the blade root 1.

[0035] After the wheel groove 2 and the blade root 1 are assembled, an assembly gap of 0.03-0.08 mm exists between the top of the wheel groove 2 and the top of the blade root 1 .

[0036] The middle of the top of the wheel groove 2 is a plane, and both sides of the plane are inclined surfaces so that the top and side surfaces of the wheel groove 2 are transitioned.

[0037] The wheel groove 2 for assembling the blade root 1 has a geometric shape that matches the geometry of the internal notch of the blade root 1 .

[0038] According to the design drawings of the blade root 1 and the wheel groove 2, the following data can be obtained:

[0039] The distance d between the blade root non-working surface 11 and the blade root working surface 12 is 12.07 mm;

[0040] The arc radius of the blade root non-working surface 11 is R=520.5mm;

[0041] The width of the top plane of blade root 1 is 22.98 mm, so the tool radius r0 for machining the non-working surface is 11 mm;

[0042] The top plane width w of the wheel groove 2 is 3.3 mm;

[0043] The inclination angle a of the inclined surface on both sides of the top area of the wheel groove 2 is 3°.

[0044] The maximum overcut amount Tmax is obtained:

[0045]

[0046] The overcut amount T1 of the blade root non-working surface 11 at the top plane of the wheel groove 2 is obtained:

[0047]

[0048] It can be seen that Tmax-T1=0.002 mm<0.01 mm, which satisfies the prerequisite that the maximum overcut amount Tmax-the overcut amount T1 of the blade root non-working surface 11 at the top plane of the wheel groove 2 is less than 0.01 mm.

[0049] The difference 0.002 mm<0.01 mm can be ignored, that is, it is determined that the distance d between the blade root non-working surface 11 and the working surface within the range of w=3.3 mm is equal. Therefore, to ensure that the assembly is qualified, it is only necessary to ensure that the distance between the actually processed blade root working surface 12 and the non-working surface is equal to the distance d required by the design of the blade root working surface 12 and the non-working surface. The difference between the distance between the actually processed blade root working surface 12 and the non-working surface and the distance d is exactly Tmax, so the overcut amount can be compensated in the design profile of the tool when designing the tool.

[0050] The inclination slope K0 of the inclined surface on both sides of the top area of the wheel groove 2 is obtained:

[0051] K0=tan a=tan 3=0.052.

[0052] The slope K1 of the top non-working surface of the blade root 1 is:

[0053]

[0054] It can be seen that K0>K1, that is, it satisfies the prerequisite that the inclination slope K0 of the inclined surface on both sides of the top area of the wheel groove 2 is greater than the slope K1 of the top non-working surface of the blade root 1, that is, even if the blade root non-working surface 11 is overcut, interference will not occur in the area outside w=3.3 mm. Therefore, only the actual overcut amount within the range of w=3.3 mm of the blade root non-working surface 11 needs to be considered when designing the tool.

[0055] When the above two prerequisites are satisfied, the overcut amount can be compensated in the pitch δ of the tool when designing the tool profile; specifically:

[0056] δ = d - Tmax = 12.07 - 0.1116 = 11.954 mm.

[0057] In summary, the tool for machining the first tooth position of the blade root 1 has a profile size of: diameter 22 mm, pitch 11.954 mm.

[0058] The application is not limited to the foregoing specific embodiments. The application extends to any novel one, or any new combination, of the features disclosed in this specification, and to any novel method or process disclosed, or any novel combination of steps of the disclosed methods or processes.

Claims

1. A design method for a mushroom-shaped blade root fine milling cutter, characterized by: Prerequisites: The middle of the top of the wheel groove (2) is a plane, and both sides of the plane are inclined so that the top and side of the wheel groove (2) transition; the maximum overcut amount Tmax - the overcut amount T1 of the blade root non-working surface (11) at the top plane of the wheel groove (2) is less than 0.01mm; The inclination slope K0 of the inclined surfaces on both sides of the top area of ​​the wheel groove (2) is greater than the slope K1 of the non-working surface of the blade root (1); When designing the tool, the overcut amount is compensated in the tool pitch δ; specifically: The pitch of the tool δ = the pitch d between the blade root non-working surface (11) and the blade root working surface (12) - the maximum overcut amount Tmax; Where: d is obtained according to the design drawing of the blade root (1).

2. The design method of the fine milling cutter for the mushroom-shaped leaf root (1) according to claim 1 is characterized by: The blade root (1) has a U-shaped stepped notch, the bottom of the notch being the top of the blade root (1); the wheel groove (2) is a boss matching the shape of the notch, and after assembly, the wheel groove (2) is assembled in the notch of the blade root (1).

3. The design method of the fine milling cutter for the mushroom-shaped leaf root (1) according to claim 2 is characterized by: After the wheel groove (2) and the blade root (1) are assembled, an assembly gap of 0.03-0.08 mm exists between the top of the wheel groove (2) and the top of the blade root (1).

4. The design method according to claim 1, wherein: Get Tmax; according to Get the maximum overcut amount Tmax; where: R: Radius of the arc of the blade root non-working surface (11); r0: Tool radius at the non-working surface; R and r0 are obtained from the design drawing of the blade root (1).

5. The design method according to claim 4, characterized in that: 2 times r0 should be smaller than the top plane width of the blade root (1).

6. The design method according to claim 4, characterized in that: Get T1; according to Obtain the overcut amount T1 of the blade root non-working surface (11) at the top plane of the wheel groove (2); wherein: w: the top plane width of the wheel groove (2); w is obtained based on the design drawing of the wheel groove (2).

7. The design method according to claim 6, characterized in that: Get K0; The inclination slopes of the inclined surfaces on both sides of the top area of ​​the wheel groove (2) are obtained according to K0=tanα; wherein: α: the inclination angle of the inclined surfaces on both sides of the top area of ​​the wheel groove (2); α is obtained based on the design drawing of the wheel groove (2).

8. The design method according to claim 6, characterized in that: Get K1; according to Obtain the slope of the non-working surface at the top of the blade root (1).

Images